Pallet lever construction



Dec. 22, 1953 .1. FlNK PALLET LEVER CONSTRUCTION Filed Oct. 31. 1949 x is INVENTOR. JEAN F/NK BY ATT'Y.

Patented Dec. 22, 1953 PALLET LEVER CONSTRUCTION Jean Fink, Delavan, Wis.,

assignor to Gibbs Manufacturing and Research Corporation,

.Eanesville, Wis., a cor poration of Wisconsin Application October 31, 1949, Serial No. 124,537 Claims. (01. 58- 121) The present invention relates in general to time keepin instruments, and the object of the invention is to provide a new and improved escapernent lever construction for use in such instruments. The invention is applicable to watches and clocks, for example, and to mechanical time fuses for projectiles.

Another feature is a new and improved escapement lever, comprising a stamping from sheet aluminum or other light metal or alloy, having integrally formed pallets.

The invention will be described more in detail hereinafter with reference to the accompanying drawing, which shows part of the frame of a mechanical time fuse in which the invention is incorporated.

Fig. 1 is a partial plan View, with several oi the frame plates removed or cut away in order to expose the balance and escapeznent mechauism;

Fig. 2 is a section on the line 2-2, Fig. 1;

Fig. 3 shows the sheet metal blank from which the escapement lever is formed.

In mechanical time fuses, the various parts are usually supported in a very strong and rigid frame made up of circular plates or discs, with intervening spacers and secured together with machine screws. The plates or spacers, or both, are provided with recesses or openings in which parts, such as levers, gears and pinions are cated, while the plates on opposite sides of such reces'es have bearings for the arbors on which the gears or other movable parts are mounted. The general type of construction is well understood and hence it has not been considered necessary to show a complete fuse frame or body in the drawing, only those plates and spacers being shown which are required for supporting the balance and escapes rent mechanisms.

Referring to Figs. 1. and 2, particularly to Fig. 2, the frame of the fuse includes the bearing plates l0, l2 and it, a plate I5, and the relatively thick plates or spacers ll, 13 and H. There may be additional plates above and below those shown, and screws, not shown, may be provided to hold them all securely together. The plates may be made of brass or other suitable material. In Fig. 1, the plates l5 and I6 have been removed and the plate or spacer M has been cut away above the escapement lever and escape wheel so that these parts can be seen. The plates are circular and the center of the frame can be located by reference to the centrally positioned arbor 24 of the balance.

The balance comprises the rectangular center piece 20, the rim 2|, and the two curved spokes 22 and 23 which connect the rim 2| with the center piece 29. The balance is mounted on the arbor 24 which is pressed into the center piece 20 and has hearings in the plates l2 and l8. The roller jewel is indicated at 23 and is mounted on the center piece 23. The jewel extends through a hole in the center piece, where it has a press fit and is held by friction. The safety roller is indicated at 25 and is carried on the arbor 24 as shown.

The balance is located in a circular opening in the plate M, which opening is only slightly greater in diameter than the rim of the balance. There should be just sufficient clearance between the rim and the wall of this opening to permit the balance to rotate freely, without contact with the wall. The spokes 22 and 23 have a certain flexibility, however, and in the event of the application of a sudden shock or force having a component in a direction perpendicular to the arbor 24, the spokes are adapted to yield and allow the rim to engage the wall of the said opening in the plate [4. The plate l4 thus absorbs the force and the pivots of the arbor 2 are protected from injury.

It will be seen also that the rim 2i of the balance rotates close to the plate IE on one side and to the thick plate or spacer E3 on the other side, so that if a shock is received having a force cornponent in a direction parallel to the arbor 2d, the spokes 22 and. 23 will bend and the rim will engage the plate !5 or the spacer 13, as the case may be. thereby preventing any substantial force from being transmitted to the pivots and bearings and avoiding danger of damage thereto. In a fuse, this arrangement protects the pivots and bearings from damage set back when the shell in. which the fuse is assem led is fired.

In a watch or clock, the limitation on displacement of the balance rim which is provided by the plates l3, l4, and I5 protects against accidental shock which might otherwise injure the arbor pivots or the jeweled bearings with which the balance arbor is provided.

The escapement mechanism is what is known as a detached lever escapement and comprises the escape wheel 36 and the escapement lever 35. These parts are located in a recess or cut out in the thick plate or spacer 3. The escapement lever is mounted on the arbor 35, where it has a press fit and may be further secured by staking. The arbor has bearings in the plates 12 and 35. The escape wheel 36 is mounted on the arbor 31. This arbor has an integrally formed pinion U 38 and the escape wheel is pressed on to the arbor above the pinion where it is further secured by staking. The arbor has bearings in the frame plates IE3 and I5.

Power for driving the escapement mechanism is transmitted to the escape wheel through a gear train in known manner. Gears 3d and iii of this gear train are shown in Fig. 2 and their location is indicated by dotted lines in Fig. l. The wheel and gears may be conventional, or they may be made of some light metal such as aluminum in order to reduce their inertia.

Further describing the escapement mechanisi the escapement lever has the integrally formed downwardly extending pallets 33 and 34, which cooperate wi h the escape wheel in the usual manner. The lever has the fork 32 at its right hand end, adapted to cooperate with the roller jewel 26. The fork is or" conventional design, as can be seen from Fig. 1. The safety pin 32 is preferably formed integrally with the lever 36 and is-adapted for cooperation with the safety roller in known manner. Banking pins for limiting travel of the escapernent lever are provided and are indicated at :i-E and These pins extend crows--5. from plate on opposite sides or" lever 3* The escapenient lever so may be made of any suitable material but is preferably made of aluminum or an aluminum base alloy on which a hard adherent coating or skin of aluminum oxide can be formed by an electrolytic process known as anodizing. Other light metals or alloys capable of surface hardening may be employed. A desirable alloy is Duraiumizn, the strength of which can be increased by a heat treatment. Other aluminum base alloys which are suitable for the purpose are known. These special alloys are preferable to commercial sheet aluminum because of their greater str ngth, which makes it possible to use thinner stock and thus reduce the weight of the part.

The particular alloy to be used should be purchased in the form of polished sheets. Such having a smooth mirror like surface, are a cor mercial article. The blanks from which the levers are formed are stamped or punched from the sheets in the usual manner. One of the blanks, from which escapement lever such as Biican be formed, is shown in Fig. 3. If the material after heat treatment is not too hard to be worked, heat treated sheets may be used. Otherwise the heat treatment should be deferred until the stamping forming operations have been performed.

The blanks are formed into escapement levers by simple bending operations which are performed by of a die, as will be readily understood. Referring to the two arms 5% and iii re bent downward at the points indicated'by the dotted lines and '53 to for l pallets such as the pallets 33 and 3d of the eseapeinent lever while the extension 5d is bent at the zottom oi the notch'in the fork and along the dotted line to form a safety pin such as These bending or forming operations may be performed in a die. as previously indicated.

The invention is well adapted to the use of what is known as a progressive die, in which successive operations are performed on a part at different stages so that the part can be completed without removal from the die. AS applied to the escapement lever til, the blank as shown in-l ig. 3 may be stamped from sheet stock, the pallets and 3 5 and the safety pin 32. may be pallets.

'4 formed by t .e necessary bending operations, and the hole for the arbor 35 may be punched or drilled, all in a single die.

The die should be carefully designed so that when the arms 52 and 5% are bent downward as described, along lines 52 and respectively, the working faces of the pallets formed by the bending operation will bear the correct angular relation to the axis of the escapement lever, whereby they will also hear the correct angular relation to the ends of the teeth of the escape wheel after the lever has been assembled in a complete escapement mechanism. The proper operation of the die is facilitated by designing the blanks so that the, arms 55] and iii are disposed relative to the axis of the blank at angles which are calculated to make the bending lines and 53 intersect the respective arms at right angles.

' If the levers are made from polished sheets as recommended herein, the working faces of the pallets will be smooth and polished, since they are formed from the surfaces at 55 of the blanks. The locking corners of the pallets and the sides of the notch in the fork-involve cut surfaces made by the die when the blanks are stamped from the sheets and may not be entirely free or burrs or sharp edges. If so, the levers may be subjected to a tumbling operation. I prefer, however, to employ an electrolytic polishing process which removes any sharp edges that may be present and also removes any raised scratches that may accidentally be present in the working faces of the Both tumbling and electrolytic polishing may be employed if indicated, the tumbling operation serving to remove rough burrs or projections, while the electrolytic polishing process is effective to give, the final smooth finish that is required.

It will be understood that the balance Eh-2i is provided with a suitable hairspring, although the same has beenoniitted from the drawing as not forming part of the invention. In the case of a watch or clock an ordinary spiral hairspring is used, but if the balance forms part of an escapement mechanism for a fuse it is preferable to employ a cylindrical hairspring, so that the coils may be as near the center of rotation as possible. A torsional hairspring may also be used.

The operation of an escapement of the type shown herein is well known and hence need not be explained in detail. The direction in which power is'applied to the escape wheel is such that the escape wheel is rotated in a clockwis direction as seen in Fig. 1. In the position in which the parts are shown, the pallet 3 has just re" leased the tooth to of the escape wheel, the es cape wheel has started to rotate, and the tooth 55 is sliding over the corner of pallet to rotate the escapement lever by a came-ding action and deliver an impulse to the balance. The impulse, which is prolonged by the sliding engagement between the extreme end of the-tooth and the working face of the pallet, is, delivered to the balance by the engagement of one side of the notchin the fork with the roller jewel accelerates the balance, which is rotatir direction of the arrow. As the balance cotinues its rotation, the roller jewel leaves the notch the fork and an instant later the rotation of escape wheel is arrested by the engagement of the pallet 33 by the tooth 6!, said pallet having beenmoved into the path of the tooth by the rotation of the escapement lever.

When the-balance" has completed its excursion in the direction indicated, it reverses its direc tion of rotation under the influence of power supplied by the hairspring and performs an excursion or beat in the opposite direction. During this beat the roller jewel 26 enters the notch in the fork again and rotates the escapement lever far enough to cause the pallet 33 to release the tooth 6|, whereupon the escape wheel starts to rotate again and the tooth and pallet cooperate to give another impulse to the balance. The operation continues in this manner.

My improved escapement lever has a considerable number of advantages over the known escapement levers which have pallet jewels. The pallets in my escapement lever cannot become loose and are not liable to breakage as are the pallet jewels in known escapement levers, but are wholly immune from such trouble, being formed in one piece with the rest of the lever and having many times the strength required to perform their work and undergo any shocks to which they may be subjected. Another advantage of the one-piece construction is the low cost of manufacture. These advantages are independent of the material from which the escapement lever is made and are secured if the lever is made of steel or titanium, for example.

The invention having been described, that which is believed to be new and for which the protection of Letters Patent is desired will be pointed out in the appended claims.

I claim:

1. A one-piece sheet metal escapement lever, comprising a main body portion having a fork at one end, two spaced arms projecting from said body portion, said body portion, fork, and arms being all in the same plane, and pallets at the ends of said arms extending in a direction perpendicular to said plane.

2. A one-piece sheet metal escapement lever, comprising a main body portion having a fiat smooth surface, two arms located in the same plane with said body portion and projecting from one edge thereof, and two pallets extending at right angles to said arms, respectively, at the ends thereof, said pallets having impulse surfaces which are continuous with the said smooth surface of said body portion.

3. A sheet metal escapement lever, comprising a flat body section having a fork at one end and an angularly disposed arm at the other end, said section having a hole intermediate said ends for an arbor, a second arm located between said hole and fork, said arms being in the same plane as said body section and integral therewith, and two pallets integral with said arms and extending from the ends thereof in a direction perpendicular to said plane.

4. A sheet metal escapement lever, comprising a flat generally bar shaped body portion, and two arms integral with said body portion and projecting from one edge thereof, each arm comprising a section disposed in the plane of said body portion and a second section perpendicular to said plane, said second sections constituting pallets for cooperation with an escape wheel.

5. A one-piece sheet metal escapement lever, comprising a flat main body portion, and two pallets extending parallel to each other and at right angles to the plane of said body portion, said pallets having locking faces which are continuous with the edge of said body portion and impulse faces which are continuous with a surface of said body portion,

JEAN FINK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 65,116 Ramsey May 28, 1867 182,358 Curpen Sept. 19, 1876 256,708 Lane Apr. 18, 1882 337,529 Simpson Mar. 9, 1886 348,980 Lane Sept. 14, 1886 380,769 Rohde Apr. 10, 1888 855,950 Horn June 4, 1907 1,033,465 Porter July 23, 1912 1,327,226 De Long Jan. 6, 1920 1,568,294 Riley Jan. 5, 1926 1,706,005 Thompson Mar. 19, 1929 1,809,007 Wulfert June 9, 1931 1,958,298 Dowd May 8, 1934 2,299,519 Whitehead Oct. 20, 1942 FOREIGN PATENTS Number Country Date 378,909 France Aug. 24, 1907 

